In various instances, a fastener, e.g. a nail or screw, has been used to hold a material in place, such as house siding, shingles, sheathing, panels, structural members, etc., or to fasten studs, joists, beams, etc. In most cases, keeping materials fastened together is the sole goal and purpose of the fastener. However, in regions subject to windy conditions and/or earthquakes, these fasteners may fail to perform their sole function which sometimes results in unfortunate consequences. For example, these fasteners, often times, are subject to high tensile and/or shear forces which cause the shaft to break thereby allowing the fastened material to separate during high winds or wind gusts, or during vibrations from an earthquake. When this occurs, the unfastened materials depart from their fastened or intended location and may inflict injury to innocent bystanders or may damage property in its wake.
Thus, it is desirable to provide a fastener which is able to overcome the above disadvantages experienced during adverse atmospheric conditions and/or during vibrations associated with, for example, earthquakes, and yet has sufficient strength so as to maintain adequate fastening ability during all climate and stability conditions.
Alternatively, for fastening together portions of certain highly stressed constructions, such as aircraft or other assemblies requiring high strength and/or light weight, many variations of fasteners have been suggested. For example, many of these prior art fasteners have been made of a core material to which a different material has been applied as a thin protective coating, as by plating, galvanizing, or other application methods. However, in these fasteners, the reduction in weight has caused a corresponding reduction in strength and/or the ability to withstand other tensile or shear forces caused by the stresses to which the assembly may be subjected.
Attempts to overcome the disadvantages of these prior art fasteners have been successful in part but have introduced other shortcomings. Typically, a molded, non-metallic fastener having an external coating of metal provides a lightweight fastener, but is unlikely to have the desired strength to withstand severe tensile and/or shear forces without a significant increase in size. Also, metal coated non-metallic fasteners typically cannot be used in conjunction with metallic structures since the relatively thin metallic coating can be quickly destroyed or worn away by the metallic structures, thereby permitting the assembled structures to act against the more fragile non-metallic core material. Thus, under the high stress conditions in which these fasteners may be used, failures can occur resulting in cutting through or shearing of the non-metallic core.
It is therefore desirable to provide a fastener having supplemental support that can be utilized in critical and/or high-stressed constructions (as well as normal or typical constructions), and that does not suffer from the above drawbacks.
These and other advantages of the present invention will become more fully apparent from the detailed description of the invention hereinbelow.